1. Field of the Invention
This invention comprises a product and method for the safe in situ treatment of groundwater and saturated aquifer material that has been contaminated with pollutants that can be anaerobically bioremediated, including energetic materials and their degradation products, halogenated organic compounds, nitrates, sulfate, metals and radionuclides.
2. Description of the Related Art
Routine activities at commercial, industrial, and military facilities often result in accumulation of pollutants in soil, groundwater and aquifer material that can be anaerobically bioremediated. Many of these pollutants are weakly bound by soil and can be transported through soils and in groundwater. This is problematic if groundwater become contaminated.
Leaching of explosives from military ranges can be controlled by surface application and tilling of hydrated lime to a depth of six inches. However, lime treatment has some disadvantages. To be most effective, the lime should be tilled into the soil. This is a major problem in areas with unexploded ordnance, since disturbing the soil could set off an explosion, injuring site workers. To apply this technology at most ranges, the unexploded ordnance must be removed from the soil, at a prohibitively expensive cost, before treatment commences. Additionally, in acidic soils containing alumino-silicates and iron hydroxides, large amounts of lime are required to reach the target pH required for effective hydrolysis. In humid areas, additional steps must be taken: the alkali is gradually leached out of the surface soil, and additional lime must be applied to maintain performance. The high pH required for effective treatment will kill most vegetation and is not practical for large areas. The application of lime to treat groundwater and saturated aquifers of necessity is more complex than with contaminated soil, may not be effective, and presents even more difficult challenges.
In an alternative approach, leaching of explosives from military ranges can be controlled by the surface application of a 10-cm thick layer of peat moss amended with soybean oil. A common explosive, RDX (Research Department Explosive, Rapid Detonation Explosive or Royal Detonation Explosive), and its breakdown product, MNX, were greatly reduced after passage through the pilot-scale soil columns. No other explosive compounds in the detonation residues were detected in the leachate in over 95% of the aqueous samples collected. Unfortunately, this peat-soybean oil approach had significant operational problems that make it impractical for deployment at most military ranges and OB/OD areas. Specifically, weapons firing and OB/OD activities can cause the peat to catch fire. Obviously, an increased fire hazard is not acceptable in this type of environment. There are also significant questions about the physical integrity of the peat moss layer and the potential for dust problems in arid areas. To reduce fire hazard and dust, it is possible that the peat-soybean oil layer could be buried. However, burying would not be practical on many ranges due to the very high costs and physical hazards associated with working in an area with unexploded ordnance.